This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This project involves development of a new method, Multi-wavelength Anomalous Diffraction using Medium Angle X-ray solution scattering (MADMAX), for the precise measurement of interatomic distances within proteins and other macromolecules in aqueous solution. It will make possible the characterization of structural changes and intra-molecular movements that cannot be studied by existing techniques. Proteins are dynamic molecules whose activities contribute to all biological processes. Virtually all protein function requires intra-molecular movement, whether for the application of mechanical force, chemical transformation or molecular translocation. MADMAX will make possible accurate atomic-level measurement of these movements within proteins in solution. MADMAX should be generally applicable to macromolecules in solution and capable of elucidating protein action during a broad range of phenomena including allosteric interactions;protein-ligand interactions;channel gating;domain movements;and protein folding. It should be capable of measuring changes in the length of interatomic vectors with an accuracy of up to ~1 [unreadable]. It can be adapted for time-resolved studies [unreadable]to at least millisecond resolution. The goals of this project are: (i) Demonstrate the accurate measurement of anomalous differences in solution scattering from well characterized proteins. (ii) Predict the anomalous differences from atomic coordinate sets. (iii) Determine the limitations of the method: How large a protein is this method applicable to? How many labels are required for detection? How much disorder in the label position can be tolerated? (iv) Use MADMAX for precise measurement of structural changes due to ligand binding. (v) Use MADMAX for the study of structural changes in membrane proteins. This project involves development of a new method, Multi-wavelength Anomalous Diffraction using Medium Angle X-ray solution scattering (MADMAX), for the precise measurement of interatomic distances within proteins and other macromolecules in aqueous solution. It will make possible the characterization of structural changes and intra-molecular movements that cannot be studied by existing techniques. Proteins are dynamic molecules whose activities contribute to all biological processes. Virtually all protein function requires intra-molecular movement, whether for the application of mechanical force, chemical transformation or molecular translocation. MADMAX will make possible accurate atomic-level measurement of these movements within proteins in solution. MADMAX should be generally applicable to macromolecules in solution and capable of elucidating protein action during a broad range of phenomena including allosteric interactions;protein-ligand interactions;channel gating;domain movements;and protein folding. It should be capable of measuring changes in the length of interatomic vectors with an accuracy of up to ~1 [unreadable]. It can be adapted for time-resolved studies [unreadable]to at least millisecond resolution. The goals of this project are: (i) Demonstrate the accurate measurement of anomalous differences in solution scattering from well characterized proteins. (ii) Predict the anomalous differences from atomic coordinate sets. (iii) Determine the limitations of the method: How large a protein is this method applicable to? How many labels are required for detection? How much disorder in the label position can be tolerated? (iv) Use MADMAX for precise measurement of structural changes due to ligand binding. (v) Use MADMAX for the study of structural changes in membrane proteins.